ORAU Team

NIOSH Dose Reconstruction Project

Technical Basis Document for Portsmouth Gaseous Diffusion 

Plant – Site Description

Document Number:

ORAUT-TKBS-0015-2 

Effective Date: 11/21/2003

Revision No.: 00 

Controlled Copy No.: _______

Page 1 of 33

Subject Expert: Marquis P. Orr

Document Owner

Approval: _Signature on File___________ Date: 11/18/2003

Mark Notich, TBD Team Leader

Approval: Signature on File____________ Date: 11/19/2003

Judson L. Kenoyer, Task 3 Manager

Concurrence: Signature on File_________ Date: 11/19/2003

Richard E. Toohey, Project Director

Approval: Signature on File____________ Date: 11/21/2003

James W. Neton, OCAS Health Science Administrator

Supersedes:

None

TABLE OF CONTENTS

Section

Record of Issue/Revisions ...................................................................................................................

Page

3

Acronyms and Abbreviations ...............................................................................................................4

2.1 Introduction................................................................................................................................. 5

2.2 Site Description...........................................................................................................................5

2.3 Site Activities ..............................................................................................................................6

2.3.1 Gaseous Diffusion Cells – Buildings X-326, X-330, and X-333........................................ 7

2.3.1.1 Building X-333 ...........................................................................................................7

2.3.1.2 Building X-330 ...........................................................................................................7

2.3.1.3 Building X-326 ...........................................................................................................8

2.3.2 Fluorine Generation Facility and Fixed Feed Facility – Building X-342 & X-342A ............ 9

2.3.3 Fixed Feed Facility – Building X-343 ............................................................................... 9

2.3.4 Feed Manufacturing Plant – Building X-344..................................................................... 9

2.3.5 Special Nuclear Materials Storage – Building X-345...................................................... 10

2.3.6 Maintenance – Building X-700....................................................................................... 11

2.3.7 Decontamination, Cleaning, and Recovery – Building X-705......................................... 11

2.3.8 Oxide Conversion Facility – Building X-705E................................................................. 12

2.3.9 Analytical Labs, Process and Materials – Building X-710 .............................................. 12

2.3.10 Compressor Shop– Building X-720................................................................................ 12

2.3.11 Aluminum Smelter and Recovery – Building X-744G..................................................... 13

2.4 Site Processes..........................................................................................................................13

2.4.1 Recent History of the Cascade ...................................................................................... 13

2.4.2 Feed Material for the Cascade ...................................................................................... 13

2.4.3 Atmospheric Emissions from the Cascade .................................................................... 14

2.4.4 Liquid Discharge from the Facility.................................................................................. 14
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2.4.5 Solid Waste Generation................................................................................................. 15

References ........................................................................................................................................29

Glossary ............................................................................................................................................30

LIST OF TABLES

Table

2.3-1 Major facilities at PORTS ..............................................................................................

Page

15

2.3.1-1 Radionuclides of concern in Building X-333................................................................... 16

2.3.1-2 Radionuclides of concern in Building X-330................................................................... 17

2.3.1-3 Radionuclides of concern in Building X-326................................................................... 18

2.3.2-1 Radionuclides of concern for Buildings X-342 and X-342A............................................ 19

2.3.3-1 Radionuclides of concern for Building X-343 ................................................................. 20

2.3.4-1 Radionuclides of concern for Building X-344 ................................................................. 21

2.3.5-1 Radionuclides of concern in Building X-345................................................................... 22

2.3.6-1 Radionuclides of concern in Building X-700................................................................... 23

2.3.7-1 Radionuclides of concern in Building X-705................................................................... 24

2.3.8-1 Radionuclides of concern for Building X-705E............................................................... 25

2.3.9-1 Radionuclides of concern for Building X-710 ................................................................. 26

2.3.10-1 Radionuclides of concern for Building X-720 ................................................................. 27

2.3.11-1 Radionuclides of concern in Building X-744G................................................................ 28

2.4.2-1 Reactor returns fed to cascade...................................................................................... 28

LIST OF FIGURES

Figure

2.2-1 Portsmouth Gaseous Diffusion Plant...............................................................................

Page

5

2.2-2 Photograph of PORTS from about 1988.......................................................................... 6
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RECORD OF ISSUE/REVISIONS

ISSUE 

AUTHORIZATION 

DATE

EFFECTIVE 

DATE

REV. 

NO. DESCRIPTION

Draft 09/25/2003 00-A New technical basis document for the Portsmouth 

Gaseous Diffusion Plant. Initiated by Mark 

Notich.

11/21/2003 11/21/2003 00 First approved issue. Initiated by Mark Notich.
Effective Date: 11/21/2003 Revision No. 00 Document No. ORAUT-TKBS-0015-2 Page 4 of 33

ACRONYMS AND ABBREVIATIONS

AEC U.S. Atomic Energy Commission

Ci curie

cpm counts per minute

DAC Derived Air Concentration

DOE United States Department of Energy

DU depleted uranium (uranium with less than 0.7% 235U)

ERP Extended Range Product

FGR Federal Guidance Report

FY Fiscal Year

GDP Gaseous Diffusion Plant

HASA High Assay Sampling Area

HEU highly enriched uranium (over 20% 235U)

LAW Low Assay Withdrawal

MTU metric tons of uranium

MeV Million electron volts

ORNL Oak Ridge National Laboratory

PCB polychlorinated biphenyl

PORTS Portsmouth Gaseous Diffusion Plant

PPE personal protective equipment

RPM Radiation Protection Manual

RU recycled uranium

TPW Top Product Withdrawal 

TRU transuranic (elements with an atomic number greater than uranium i.e., <92)

UF6 uranium hexafluoride 

UF4 uranium tetrafluoride

U.S. DOE United States Department of Energy

USEC United States Enrichment Corporation

U.S.C. United States Code
Effective Date: 11/21/2003 Revision No. 00 Document No. ORAUT-TKBS-0015-2 Page 5 of 33

2.1 INTRODUCTION

This part of the Portsmouth Gaseous Diffusion Plant (PORTS) technical basis document describes 

the site (Section 2.2), the site facilities (Section 2.3), and historic site processes (Section 2.4). 

2.2 SITE DESCRIPTION

PORTS is in Pike County, Ohio, approximately 112 kilometers (70 miles) south of Columbus, Ohio. 

The federal reservation covers approximately 3,714 acres and contains 109 buildings and individual 

plants with approximately 500 acres of roofed area. 

Figure 2.2-1. Portsmouth Gaseous Diffusion Plant 

Uranium enrichment was the primary activity at PORTS. Uranium is a naturally occurring radioactive 

element that consists of three isotopes: 238U (99.276%), 235U (0.719%), and a trace amount of 234U 

(0.0057%) (DOE 1997, p. 20). The enrichment process increases the concentration of 235U which is 

needed to manufacture low enriched (less than 20% 235U) nuclear fuel necessary for commercial 

nuclear power plants and highly enriched (more than 20% 235U) material for the U.S. Navy propulsion 

program and atomic weapons. In 1952, construction began on the gaseous diffusion plant in Piketon, 

Ohio, which later became known as the Portsmouth Gaseous Diffusion Plant. Uranium enrichment 

began in 1954 and continued until May 2001 when operations were consolidated at the Paducah plant 

(USEC 2003). 

The historical records indicate that the plant enriched uranium for government programs and 

commercial nuclear power plants at levels ranging from a few to up to 97 percent 235U. In 1991, 

production of the highly enriched uranium (HEU) stopped and the plant mission changed to uranium 

enrichment for commercial reactors. From its initial construction until 1986, the site was operated by 

Goodyear Atomic Corporation. In 1986 Martin Marietta Energy Systems, Inc. took over operation of 
Effective Date: 11/21/2003 Revision No. 00 Document No. ORAUT-TKBS-0015-2 Page 6 of 33

the facility after Goodyear decided not take part in the rebid. The Energy Policy Act of 1992 (Public 

Law 102-486) transferred responsibility for Portsmouth from the U.S. Department of Energy (DOE) to 

a newly created entity, the United States Enrichment Corporation (USEC), which has leased and 

operated the facility since July 1, 1993 (USEC 2003). 

There are four main facilities at PORTS: the Feed Manufacturing Plant, Oxide Conversion Facility, 

Cascades, and Decontamination and Recovery Facility. The feed plant, oxide conversion facility, and 

uranium recovery operation all support the enrichment cascade. Between 1955 and 2001, PORTS 

processed over 300,000 metric tons of uranium (MTU) through its cascade (DOE, 2000a, p. 16). 

Figure 2.2-2. Photograph of PORTS from about 1988. 

2.3 SITE ACTIVITIES

Plant Facilities

Table 2.3-1 shows the major facilities at PORTS. Each of these areas was critical to the operation of 

the plant. 
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2.3.1

The main process buildings at PORTS (X-326, X-330, and X-333) contain the cascades, which are a 

series of compressor, heat exchanger, control valve and motor, converter stages, and supporting 

piping arranged in stages, cells, and units that progressively increase the concentration of the 235U 

isotope in the uranium hexafluoride (UF6) feed. 

Gaseous Diffusion Cells – Buildings X-326, X-330, and X-333

Enrichment occurs as the UF6 passes through semi-porous barriers in the converter stage. These 

barriers allow the lighter 235U to pass through more easily, which results in a gas with a slightly higher 

percentage of 235U (enriched) on one side of the barrier and a slightly lower percentage (depleted) on 

the other side. The enriched UF6 gas flows up towards the top of the cascade while the depleted UF6

gas flows toward the bottom. 

An individual converter stage enriches the UF6 gas stream approximately 0.0043%. The PORTS 

cascade consists of 4,080 stages in the three process buildings. The facility was able to enrich 

uranium to nearly 100% 235U. 

2.3.1.1 Building X-333

The initial enrichment process occurred in Building X-333. It is equipped with 80 enrichment cells, 

each of which has eight isotopic stages, for a total of 640 stages. All cells contain the largest-size 

converter in the system (designated X-33 or 000). As with all the cascade buildings, the enrichment 

stages are installed on the second floor with the auxiliary systems and control rooms on the ground 

floor. The two floors provide approximately 65 acres of floor space. Reactor-grade material can be 

drawn off through the Low Assay Withdrawal (LAW) station in the west-central section of the building 

(DOE 2000a, p. 17). Table 2.3.1-1 shows the radionuclides of concern associated with Building 

X-333.

X-333 Internal Dose Issues: Most uptakes of uranium indicate a fast absorption type unless otherwise 

identified in the bioassay records. Because the concentration of both the 235U and 234U are increased 

by the enrichment process, and the 234U has a shorter half-life than the 235U, most of the annual 

internal dose will be from 234U.

X-333 External Dose Issues

2.3.1.2 Building X-330

: There is a potential for exposure to technetium-99 (99Tc) when 

conducting maintenance of cascades due to plating out within the system. Because X-333 is used as 

a back-up to the X-330 tails facility, depleted uranium (DU) may concentrate in this facility (see 

Section 2.3.1.2) (High and Strom 1993, p. 16.6). The secular equilibrium pair 234Th/234mPa is an 

external skin dose hazard if no personal protective equipment (PPE; e.g., gloves, coveralls, or full 

face respirators) is used. A 2,000 cpm limit to the skin amounting to about 20 mrem of skin exposure 

was used as a screening action limit (HP-103, p1-RPM).

The X-330 process building carried out the intermediate stages of the enrichment process. It is 

equipped with 1,100 stages. Five hundred stages (50 cells) have the X-31 or 00-size equipment, six 

hundred stages (60 cells) are equipped with X-29 or 0-size converters. The two floors provide a total 

of 55 acres of floor space. The original tails withdrawal station is in the northeast corner of the 

building. It has been modified to allow the withdrawal of product as well as tails (DOE 2000a, p. 18). 

Table 2.3.1-2 identifies the radionuclides of concern for Building X-330.
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X-330 Internal Dose Issues: Most uptakes of uranium indicate a fast absorption type unless otherwise 

indicated in the bioassay records. Most of the annual internal dose will be from 234U.

X-330 External Dose Issues

2.3.1.3 Building X-326

: There is a potential for exposure to 99Tc during maintenance of 

cascades due to plating out within the system. Due to the tails or DU concentrating in this facility the 

234Th/234mPa secular equilibrium pair fed by 238U could be an external dose issue. That pair is an 

external skin dose hazard if no PPE is used. A 2,000-cpm limit to the skin amounting to about 20 

mrem of skin exposure was used as a screening action limit (HP-103, p. 1-RPM). 

The PORTS cascade is able to enrich uranium to more than 97 percent 235U. The X-326 building is 

the final and highest stage enrichment cascade. The building is equipped with 2,340 stages, 720 

stages (60 cells) with X-27 size equipment and 1,620 stages, including the purge stages, with X-25 

size equipment. The two floors have a total of 58 acres of floor space. A withdrawal station is in the 

southwest corner of the ground floor, it is designed to withdraw the highly enriched uranium (HEU) 

product (BJC 2000, p. 20). 

The purge facilities are in the south end of the X-326 building. They were used to vent light 

contaminants in the UF6 stream before the flow entered the high assay enrichment equipment. The 

purge systems vented entrapped air, Freon, and such lightweight isotopes as 99Tc from the UF6

stream. Because of its low atomic weight and relative volatility, technetium tends to concentrate at 

the top of the gaseous diffusion cascade, where it becomes an inhalation, ingestion, and effluent 

concern when the cascade is vented or opened for maintenance. Technetium as pertechnetate (TcO4) 

is also difficult to remove from skin and can therefore cause significant skin dose from contamination. 

Detection and classification of Technetium exposure is difficult because its low energy beta (Max. 

0.293 MeV) is often masked by the higher energy (Max. 2.29 MeV) beta from 234mPa (DOE 2000c, p. 

2-16). 

Facilities in Building X-326 include the Extended Range Product (ERP) Station, the High Assay 

Sampling Area (HASA), the Top Product Withdrawal (TPW) Station, mobile side withdrawals, side 

feeds, and light gas purge stages. Radiochemicals including UF6, U3O8, and uranyl fluoride (UO2F2) 

are likely (High and Strom 1993, p14.7). In addition, contaminated waste is currently stored in the 

X-326 L Cages under special security requirements. Table 2.3.1-3 identifies the radionuclides of 

concern in Building X-326.

X-326 Internal Dose Issues: As in the other cascade buildings, most uptakes of uranium indicate a 

fast absorption type unless otherwise documented in the bioassay records. Most of the annual 

internal dose will be from 234U. In addition, Table 2.3.1-3 shows time and sources for processing of 

HEU. Intake of 99Tc should be considered during maintenance of cascades due to plating out within 

the system or in the maintenance of the purge equipment. 99Tc was a significant environmental 

release radionuclide from 1975 to 1994. 

X-326 External Dose Issues

In general, all the process building work areas were physically hot, but normally clean and 

uncontaminated, except when equipment was opened for repair, maintenance, or modifications. 

Multiple small “puff” or “jet” releases of UF6 occurred during connection and disconnection of feed and 

: Consider exposure to 99Tc from maintenance of cascades due to plating 

out within the system. During times of processing HEU, neutron radiation may have been present in 

higher than average amounts due to the alpha–neutron reaction on fluorine, (75 mrem yr-1 (Cardarelli 

1997; CDC, p. 8). 
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product storage cylinders or from broken instrument lines or connection piping. In general, PPE was 

used only for specific maintenance activities and not during the connection or disconnection of 

cylinders. The majority of contamination and personnel exposure to UF6 and hydrogen fluoride (HF) 

gas in the process buildings occurred during cylinder moves (DOE 2000a, p. 18). 

2.3.2

The X-342 facility contains equipment to vaporize and sample UF6 before feeding it to the cascades 

and to generate pure fluorine gas (F2) for the uranium recovery operations. Fluorine is generated by 

the electrolytic conversion of hydrogen fluoride, which also produces sodium fluoride, lithium fluoride, 

and potassium fluoride as waste products. While chemically hazardous, the fluorine generation 

operation presented little or no radiological hazard to the workers. Table 2.3.2-1 identifies the 

radionuclides of concern for Building X-342 and the Fixed Feed Facility in Building X-342A. 

Fluorine Generation Facility and Fixed Feed Facility – Building X-342 & X-342A

X-342 & X-342A Internal Dose Issues: Vaporization of UF6 from transport cylinders would allow for 

the uptake of uranium as a fast absorption type unless otherwise documented in the bioassay 

records. Most of the annual internal dose will be from 234U. In addition, Table 2.3.2-1 shows time and 

sources for processing of feed materials. 

X-342 & X-342A External Dose Issues

2.3.3

: Ambient gamma, beta, and neutron radiation may be of 

concern in this area. 

At first, UF6 feed and product material could be input or withdrawn from the cascades at virtually any 

point. Later, fixed feed facilities were installed in X-342A and X-343 using autoclaves to heat the 

cylinders and feed UF6 gas into the cascade. The mobile input and withdraw facilities have not been 

used since 1991. Contamination and exposure in the fixed feed facility was more chemical than 

radiological in nature and occurred during cylinder connection and disconnections. Table 2.3.3-1 

shows the radionuclides of concern in Building X-343, and Table 2.3.2-1 shows the radionuclides of 

concern in Building X-342A and X-342. 

Fixed Feed Facility – Building X-343

X-343 Internal Dose Issues: As in X-342 uranium uptake should be considered as a fast absorption 

issue unless otherwise documented in bioassay records. Most of the annual internal dose will be from 

234U. 

X-343 External Dose Issues

2.3.4

: Ambient gamma, beta, and neutron radiation may be of concern in this 

area. 

Uranium tetrafluoride (UF4; green salt) was converted to UF6 in the X-344 Feed Manufacturing Plant. 

The UF4 feedstock used in X-344 was of normal enrichment from either Mallinckrodt Chemical Works 

or National Lead of Ohio (Fernald). According to plant records, none of the UF4 contained recycled 

uranium (RU) (BJC 2000, p. 42). The plant used direct fluorination tower reactors to convert UF4 to 

UF6 before feeding it into the cascade. The Feed Manufacturing Plant operated from May 1958 until 

February 1962, producing a total of 11,890 MTU of UF6 feed for the cascade (BJC 2000, p. 36). 

Feed Manufacturing Plant – Building X-344

The direct fluorination towers operated by dropping powdered green salt through a rising column of 

hot elemental fluorine gas (F2). The resultant UF6 gas was drawn off, filtered, condensed, and 

transferred to storage cylinders to be fed into the cascade. Excess F2 was recovered and unreacted 
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material (ash) was collected and re-fed to the tower. Working conditions in the area were harsh. 

During operation, the area around the towers was hot and noisy and the air was filled with dust and 

smoke. Because fluorine is such an extremely reactive gas, the towers were high maintenance items 

that required constant repair and upkeep. 

In the mid-1950s, PORTS evaluated the seriousness of contamination in work areas by calculating a 

“Contamination Index” based on the level of contamination and square footage of the work area. A 

three-tiered approach categorized work areas as Red, Orange, or Clean. An index of greater than 75 

was designated a “Red Job” assignment, an index of 10 to 75 was considered “Orange,” and anything 

less than 10 was considered “Clean.” The specific formula used for determining the contamination 

index was not available however, Building X-344 was designated a permanent Red job assignment in 

1955, and employees were furnished company-issued undergarments, coveralls, head covers, and 

shoe covers or shoes. Showering was also a post-job requirement for any Red job assignments. 

Despite these formal controls, inspection reports and appraisals indicate that the requirements were 

not enforced and that adherence was inconsistent (DOE, 2000a, p. 40). 

Building X-344 houses the feed autoclaves for natural assay as well as the sampling facility for large

UF6 cylinders. Radiochemicals including UF6, U3O8, and UO2F2 were likely sources for both internal 

and external exposure. 

Uranium recovery material from X-705 was transferred to X-344 in the form of UO2F2 to blend with the 

UF4 steam. Although no direct use of RU occurred in Building X-344, recovered uranium from 

building X-705 may have contained transuranic (TRU) isotopes from the small quantity of RU 

processed by PORTS. Additionally, because purge gas from the cascades was processed in X-344, 

99Tc could have been present (DOE 2000a, p. 95). Facilities in this building include feed autoclaves 

for natural assay. Sampling of large UF6 cylinders also occurred here (Hill and Strom 1993, p. 16.6). 

Table 2.3.4-1 shows the nuclides of concern for Building X-344. 

X-344 Internal Dose Issues: Uranium intakes indicate type S for these facilities; see the Internal Dose 

section of this TBD for further information. 

X-344 External Dose Issues

2.3.5

: Exposure to 99Tc is a potential from maintenance of cascades due to

plating out within the system. Fluorination towers were 100 mR/hr on contact during normal 

operations and 50 mR/hr at 12 in. High beta fields are possible due to accumulation of progeny. Ash 

tower spills of 6 R/hr beta/0.7 R/hr gamma at contact are an issue. This exposure rate could have 

occurred during clearing of ash plugs from the towers (DOE 2000a, p. 45). 

The vaults on the north and south sides of Building X-345 store or stored highly enriched uranium. 

The central area houses a HASA and a small laboratory. The entire building has been designated as 

having fixed radiological contamination (Yggdrasil Institute 2003). DOE describes the sampling facility 

as a source of fluoride and uranium emissions (DOE 2000a, p. 43). Table 2.3.5-1 identifies the 

radionuclides of concern for Building X-345. 

Special Nuclear Materials Storage – Building X-345

Due to its high atomic weight, and because thorium-230 (230Th) is a decay product of 234U, it tends to 

concentrate with the highly enriched 235U stored in Building X-345. This makes the alpha emitting 

230Th an inhalation hazard for workers in the area. The NRC has given 230Th a lung clearance 

classification of S (slow), which is equivalent to the Federal Guidance Report (FGR) No. 11 class Y 

(years) (NRC 1992, p. 2). 
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X-345 Internal Dose Issues: Most uptakes of uranium indicate a fast absorption type unless otherwise 

indicated in the bioassay records. Note that both 230Th and 234U should be considered as predominant 

radionuclides.

X-345 External Dose Issues

2.3.6

: Ambient gamma and neutron radiation are of concern.

The building is used for equipment maintenance support for non-radioactive or low-level radioactively 

contaminated equipment from the diffusion cascade. It houses the Chemical Cleaning and 

Operations, the Converter/Weld Shop, and the Radiation Calibration Laboratory. The Calibration 

Laboratory housed sealed sources of 137Cs, 226Ra and an X-Ray machine for component repair 

inspections. It operated as long as the cascades were in use. The major use of the Barrier Shop was 

final assembly and repair of converters. The Converter Shop performed welding operations on the 

converters. Contaminated equipment could be repaired in the maintenance areas of the shops. 

Radiochemicals such as UF6, U3O8, and UO2F2 are likely, as well as hazardous chemicals such as 

hydrogen fluoride, trichloroethylene, other solvents; polychlorinated biphenyl (PCB) contaminated oils, 

welding gases, mercury, and toxic metals (High and Strom 1993, p. 16.7). Work techniques and 

procedure requirements for the use and availability of PPE improved through the years, but a lack of 

compliance and enforcement was a recurring problem (DOE 2000a, p. 28). Table 2.3.6-1 identifies 

the radionuclides of concern in Building X-700. 

Maintenance – Building X-700

X-700 Internal Dose Issues: Most uptakes of uranium indicate a fast absorption type unless otherwise 

indicated in the bioassay records. 

X-700 External Dose Issues

2.3.7

: 99Tc deposits along with TRU elements and uranium progeny were 

likely present, as well as ambient gamma and neutron radiation. 

The uranium recovery facility recovered approximately 38.2 MTU of triuranium octoxide (U3O8) during 

its period of operation (1958 to 2001). Although the facility underwent many safety and process 

improvements, the basic operation remained unchanged. Uranium-bearing solutions, scrap, and 

waste materials were dissolved and chemically treated to extract the uranium. The uranium bearing 

slurry was kiln-dried to form U3O8, which was sent to the oxide conversion plant in Building X-705E for 

conversion to UF6 for cascade feed. A very small percentage of impurities and radioactive isotopes 

traveled with the U3O8 and concentrated in the ash from the oxide converter. Most impurities and 

metals remained in solution and concentrated in the sludge of the X-701B settling pond or in the 

precipitate of the heavy metals recovery operation (BJC 2000, pp. 36-–39). Contaminants in X-705 

such as UF6, UO2F2 (fine dust), uranyl nitrate, and U3O8 (from calciners) are likely. TRU elements 

such as 237Np, 228Pu, 239Pu, 240Pu, and 241Am were present from flame tower ash and the MgF2 traps 

from the oxide conversion facility (X-705E) (Hill and Strom 1993, p. 16.8). Table 2.3.7-1 identifies the 

radionuclides of concern for Building X-705. 

Decontamination, Cleaning, and Recovery – Building X-705 

X-705 Internal Dose Issues: Uranium intakes indicate class S for these facilities, (Thomson 2003); 

see Internal and External Dose chapters of this TBD for additional information. All TRU elements 

along with 99Tc are of concern in this area. Uranium bearing solutions, scrap, and waste materials 

were dissolved and chemically treated to extract uranium. A flame tower operated in the facility from 

1958 to 1965. Although an Oak Ridge National Laboratories report indicated potential internal 

exposures to insoluble and enriched oxides, monitoring at the time was not adequate (DOE 2000a, p. 

46). In vivo monitoring (lung counting) for insoluble uranium and 237Np began in 1965. 
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X-705 External Dose Issues

2.3.8

: Ambient gamma, beta, and neutron radiation may be of concern in this 

area.

The Oxide Conversion Facility in Building X-705E provided the capability to generate UF6 directly from 

uranium oxide (U3O8). The first conversion process used screw-fed, stirred-bed reactors that proved 

difficult to maintain and had inadequate production capabilities. They were replaced in 1959 with a 

direct fluorination flame tower, which was improved and enlarged in 1967. The enlarged conversion 

facility operated until 1978. In sum, the Oxide Conversion Facility operated from 1957 to 1978 and 

produced about 233 MTU of UF6 (DOE 2000a, p. 18). Operation of the oxide conversion facility 

required continual maintenance and repair. The system was beset with airborne uranium 

contamination, burn-through of the fluorination towers, leakage from the cold traps and product 

withdrawals, and system breaches (DOE 2000a, p. 20). 

Oxide Conversion Facility – Building X-705E

X-705E Internal Dose Issues: Uranium intakes indicate class S for these facilities. (Thomson, 2003) 

All TRU elements along with 99Tc are of concern in this area. Permissible air levels were exceeded 

during handing of oxide powders, changing the tower feed screw, connecting and disconnecting 

pigtails, and performing maintenance on cold traps plugged with foreign materials (DOE 2000a, p. 

46). In vivo monitoring for insoluble uranium and 237Np began in 1965. 

X-705E External Dose Issues

2.3.9

: Ambient gamma, beta, and neutron radiation may be of concern in this 

area.

The facilities in this area include electrical substations, special analytical labs, and process and 

materials technology areas. Sealed radioactive sources containing 22Na, 99Tc, 252Cf (40.2 mCi – 

1999), 133Ba, or 137Cs were used for instrument calibration and may be found in the instrument 

technology area. A small radiographic room was used to test welds, small valves, sample containers, 

and other components for internal soundness and integrity. The presence of UF6, UO3, and UO2F2

along with TRU elements is also likely due to the handling of enriched product (High and Strom 1993, 

p. 16.10). Table 2.3.9-1 shows the radionuclides of concern for Building X-710. 

Analytical Labs, Process and Materials – Building X-710 

X-710 Internal Dose Issues: Most uptakes of uranium should be considered a fast absorption type 

unless otherwise documented in the bioassay records. 

X-710 External Dose Issues

2.3.10

: Ambient gamma, X-ray, beta, and neutron radiation may be of concern 

in this area. Calibration sources including 22Na, 99Tc, 133Ba, 137Cs, or 252Cf were used for instrument 

calibrations. 

Each cell in the cascade contained a compressor, heat exchanger, and converter. The compressor 

shop was a precision machine shop where compressors could be disassembled, decontaminated, 

repaired, and modified. The concrete pad outside the compressor shop served as an outdoor 

cleaning and decontaminating area for compressors and other large equipment from the cascades. 

Steam, high-pressure water, degreasers, and chemical solvents were sprayed to clean and 

decontaminate the equipment before moving it into the shop. Runoff from the cleaning pad entered 

the storm drain system. Table 2.3.10-1 shows the radionuclides of concern for Building X-720. 

Compressor Shop – Building X-720
Effective Date: 11/21/2003 Revision No. 00 Document No. ORAUT-TKBS-0015-2 Page 13 of 33

X-720 Internal Dose Issues: Most uptakes of uranium indicate a fast absorption type unless otherwise 

indicated in the bioassay records. 

X-720 External Dose Issues

2.3.11

: Ambient gamma and beta radiation may be of concern in this area. 

Facilities include an aluminum smelter to extract aluminum from process equipment. Waste and 

scrap was stored pending offsite disposal. Uranium in the form of UF6, UO3, and UO2F2 along with 

TRU elements are expected (Hill and Strom 1993, p. 16.9; DOE 2000a, p. 52). Table 2.3.11-1 shows 

the radionuclides of concern for Building X-744. 

Aluminum Smelter and Recovery – Building X-744G 

X-744G Internal Dose Issues: Most uptakes of uranium indicate a fast absorption type unless 

otherwise indicated in the bioassay records. 

X-744G External Dose Issues

2.4 SITE PROCESSES 

: Ambient gamma and neutron radiation may be of concern in this area.

2.4.1

Production of HEU ended in 1991 when 1,680 cascade stages were retired in place. They were 

cleaned of large deposits and mothballed between fiscal year (FY) 1993 and FY 1998. A total of 240 

X-27 and 180 X-25 cascade stages remained in operation through 2001; they were used for product 

withdrawal and side feeding. 

Recent History of the Cascade

All enrichment operations were halted in 2001 when USEC transferred enrichment operations to the 

Paducah Gaseous Diffusion Plant (Paducah GDP). Operating equipment was cleaned of gross 

contamination and large deposits before being placed in dry storage. 

From 1997 to mid-1998, the active stages in Building X-326 were used to down-blend 14 MTU of HEU 

stored on site. The HEU-UF6 in storage was diluted as part of a memorandum of understanding 

between DOE and USEC. Other uranium-bearing materials with greater than 20% enrichment were 

shipped off site (BJC 2000, p. 24). 

A fire on December 9, 1998 destroyed one and damaged two other cells in the purge cascade in 

Building X-326. The accident investigation team hypothesized that a loss of cooling to aluminum 

process equipment caused the fire. The equipment became so hot that an aluminum–uranium 

hexafluoride reaction (which is highly exothermic) took place. The fire released an undetermined 

quantity of radiological materials (NRC, 1999). 

2.4.2

During operations, more than 330,000 MTU of UF6 passed through the PORTS cascades (BJC 2000, 

p. 22). The major source of feed material was Paducah GDP and K-25. The feed manufacturing 

plant in Building X-344 and Oxide Conversion Plant in Building X-705 produced a small percentage of 

the UF6 feed stock and some UF6 was received directly from commercial sources. 

Feed Material for the Cascade

Of the 330,000 MTU fed to the PORTS cascade, 1,094.66 MTU contained RU from spent nuclear fuel 

(BJC 2000, p. 22). The RU came from many sources over many years of operation. Table 2.4.2-1 

shows the source and quantity of reactor returns fed to the cascade. 
Effective Date: 11/21/2003 Revision No. 00 Document No. ORAUT-TKBS-0015-2 Page 14 of 33

RU was first fed to the cascade during start-up in 1955 when UF6 feed was manufactured at Paducah 

GDP from UO3 received from Hanford and Savannah River reactor tails. In addition, the normal 

Paducah GDP feed material contained an estimated 1-ppm 99Tc contamination. The UO3 from the 

Savannah River and Hanford Canyon systems were contaminated before 1967 with 237Np, plutonium, 

and 99Tc at an estimated 0.18 ppm, 0.4 ppm, and 6.65 ppm, respectively, and after 1967 at 0.068 

ppm, 0.021 ppm, and 6.65 ppm, respectively (BJC 2000, p. 19). 

2.4.3

Cascade operation released a variety of contaminants to the air. Chief among them was uranium, 

fluorine, fluorides, and Freon. A May 2000 DOE report identifies the following contaminants released 

through the top and side purge cascades in Building X-326: Uranium, 99Tc, HF, F2, chlorine (Cl), SO4, 

SO2F2, Freon 114, ClF4, and CF4 (DOE 2000b). Uranium and technetium were the major release 

elements from the cold recovery and wet air evacuation systems in Buildings X-330 and X-333 (DOE 

2000a, p. 72). 

Atmospheric Emissions from the Cascade 

Because of the lack of air sampling data, the full quantity of uranium, fluorine, and other atmospheric 

discharges from the cascade operation cannot be known. In addition, the design of PORTS facilitated 

accidental or intentional venting through unregulated and unmonitored outlets. One source estimates 

that 20 to 30 tons of fluorine was vented annually during operation of the facility (DOE, 2000a, p. 72). 

While fluorine releases may have some correlation with uranium releases because airborne UF6

hydrolyzes with atmospheric water to form hydrogen fluoride, UO3, and U3O8, however a close 

correlation is not possible because the plant design required the use of free fluorine and fluoride 

compounds, which were vented to atmosphere. It is therefore impossible to estimate the radiological 

impacts resulting from the release of 20 to 30 tons of fluorine. 

PORTS did not perform continuous vent monitoring of radionuclides or fluorides until the middle of the 

1980s. Grab samples and some space recorders were used to estimate the quantity of released 

materials, but the unreliability of space recorders and inaccuracy of grab sampling when compared to 

continuous monitoring systems indicate that emissions may have been underestimated. Accidents 

and deliberate events resulted in several large atmospheric releases at the facility. A cylinder rupture 

in 1978 vented more than 6,000 kg (13,000 lb) of UF6 inside the fixed feed facility. In 1985, operators 

released over 50 kg (110 lb) of uranium into the atmosphere from X-333 when the wet traps 

overloaded and operators ignored alarms (BJC 2000, pp. 20-–27). 

2.4.4

Liquid effluents from PORTS contributed a large portion of total emissions from the facility. Water and 

degreasing solvents from the decontamination facilities were sent to the X-701B holding pond at rates 

as high as 500,000 gallons per month until the pond was closed in 1988. An active uranium recovery 

program in X-705 used nitric acid to dissolve uranium-bearing solids and produce U3O8 feed for the 

oxide converters. Effluents from the uranium recovery operation and decontamination activities were 

routed to the X-701B holding pond, which drained through a small stream to the Scioto River. 

Liquid Discharge from the Facility 

During FY 1975, sludge sample from the bottom of X-701 showed concentrations of 99Tc, uranium, 

plutonium, neptunium, and various heavy metals. It was estimated that 1,415 grams of 99Tc as well 

as 0.03 grams of plutonium and 3.3 grams of neptunium were present in the sludge (BJC 2000, pp. 

32-–36). Once or twice each year the pond was dredged and the sludge was dumped in containment 

ponds on either side of X-701B to dry before being shipped off the site. Airborne exposure could have 

occurred during the drying and handling operations. 
Effective Date: 11/21/2003 Revision No. 00 Document No. ORAUT-TKBS-0015-2 Page 15 of 33

2.4.5

The PORTS facility had a continuing program to recover as much uranium as possible from all scrap

materials. A strict Go-NoGo criterion was used to evaluate all solid and liquid waste products; all 

material with sufficient uranium content was sent to the uranium recovery operation in Building X-705. 

Filter media, incinerator ash, magnesium fluoride traps, and scrap metals with recoverable uranium 

went through a solvent extraction process which involved dissolving the uranium (and other metals) in 

nitric acid then separating the uranium by solvent extraction and drying. The dried U3O8 was fed to 

the oxide converters where it was converted to UF6 and fed to the cascades (DOE 2000a, pp. 18-–20; 

BJC 2000, pp. 35-–37). 

Solid Waste Generation 

Oxide conversion work in X-705 presented the most hazardous radiological and chemical exposures 

to PORTS workers. The original plant design was inefficient and generated large quantities of 

airborne and surface contamination from the manual handling of uranium powder. A design change in 

1965 installed additional glove boxes and automated controls to grind the U3O8 into a fine powder and 

feed it to the fluorination towers. However, leaks and equipment maintenance problems still 

generated large uranium contamination and exposure problems for the workers. 

Early exposure levels were so high that, in 1965, two oxide conversion workers were found to have 

high enough insoluble uranium lung burdens that they were put on permanent restricted duty. One 

worker still had significant lung burden when he retired in 1985 (DOE 2000a, p. 18). 

Table 2.3-1. Major facilities at PORTS. 

Building 

No. Name

Dates of 

Operation Activities

X-326 Gaseous Diffusion Process Bldg. 1954–1991 High Assay Product 

X-330 Gaseous Diffusion Process Bldg. 1954–2001 Intermediate process & tails withdrawal

X-333 Gaseous Diffusion Process Bldg. 1954–2001 Initial enrichment & reactor product

X-342A Fixed Feed Facility 1954–2001 Feed UF6 to Process line

X-342 Fluorine Generation Facility 1954–2001 Generate elemental F2 for converters

X-343 Fixed Feed Facility 1954–2001 Feed UF6 to Process line

X-344 UF6 Feed Manufacturing Plant 1958–1962 Conversion of UF4 to UF6

X-345 Special Nuclear Material Storage 1978–2003 Highly enriched uranium storage

X-700 Maintenance Building 1954–2003 Large component repairs

X-705 Decontamination & Cleaning Bldg. 1954–2003 Equipment wash & uranium recovery

X-705E Oxide Conversion Plant 1957–1978 Convert U3O8 to UF6

X-710 Labs, Electrical and I&C Shops 1954–2003 Testing, Calibration, & Repair

X-720 Compressor Shop 1954–2003 Disassembly & repair of compressors

X-744G Smelter & Aluminum Recovery 1954–1978 Recover aluminum from scrap

(Source: DOE 2000b, p. 16)
Effective Date: 11/21/2003 Revision No. 00 Document No. ORAUT-TKBS-0015-2 Page 16 of 33

 Table 2.3.1-1. Radionuclides of concern in Building X-333 . 

Facility/process X-333 LAW Area

Years of operation 1954 – 2001

Radionuclides 

of concern

Most 

Probable 

Absorption 

Type

Absorption 

Type 

ranged

Activity fraction Significant to external 

exposureb

234U F F-S 5.03 × 10-1

235U F F-S 2.83 × 10-2

236U F F-S 1.74 × 10-3

238U F F-S 4.67 × 10-1 X

99Tc M F-M Trace X

237Np S M-S 6.81 × 10-5

238Puc S M-S 4.29 × 10-5 X

239Puc S M-S 4.29 × 10-5 X

240Puc S M-S 4.29 × 10-5 X

241Amc S M-S 4.29 × 10-5 X

228Th S F-S 4.42 × 10-5

230Th S F-S 8.23 × 10-5

231Th S F-S Trace

232Th S F-S 1.04 × 10-5

234Tha M F-S Trace X

234mPaa M M-S (In equilibrium with 234Th) X

a. 234Th/234mPa are found in equilibrium and are absorption type M for GDPs. 99Tc is type F 

for GDPs that based their derived air concentration (DAC) on conservative modes (RPM, 

p. 15). 

b. 238U feeds 234mPa with a high-energy beta that is also of concern.

c. Americium and d plutonium not distinguished in analysis.

d. Always use bioassay information to determine absorption type, when available
Effective Date: 11/21/2003 Revision No. 00 Document No. ORAUT-TKBS-0015-2 Page 17 of 33

 

 Table 2.3.1-2. Radionuclides of concern in Building X-330. 

Facility/process X-330 process facilities and tails withdrawal

Years of operation 1954 – 2001

Radionuclides 

of concern

Most 

Probable 

Absorption 

Type

Absorption 

Type ranged

Activity fraction Significant to external 

exposureb

234U F F-S 7.44 × 10-1

235U F F-S 3.33 × 10-2

236U F F-S 2.46 × 10-3

238U F F-S 2.20 × 10-1 X

99Tc M F-M Trace X

237Np S M-S 8.22 × 10-5

238Puc S M-S 1.03 × 10-5 X

239Puc S M-S 1.03 × 10-5 X

240Puc S M-S 1.03 × 10-5 X

241Amc S M-S 1.03 × 10-5 X

228Th S F-S 1.51 × 10-5

230Th S F-S 8.36 × 10-5

231Th S F-S Trace

232Th S F-S 1.66 × 10-5

234Tha M F-S Trace X

234mPaa M M-S (In equilibrium with 234Th) X

a. 234Th/234mPa are found in equilibrium and are type M for GDPs. 99Tc is type F for GDPs that 

based their DAC on the more conservative modes (RPM, p. 15). 

b. 238U feeds 234mPa with a high-energy beta that is also of concern.

c. Americium and plutonium not distinguished in analysis.

d. Always use bioassay information to determine absorption type, when available. 
Effective Date: 11/21/2003 Revision No. 00 Document No. ORAUT-TKBS-0015-2 Page 18 of 33

 Table 2.3.1-3. Radionuclides of concern in Building X-326. 

Facility/process X-326 process facilities and ERP, HASA and PW

Years of operation 1954 – 2001 (1991 for HASA)

Radionuclides 

of concern

Most 

Probable 

Absorption 

Type

Absorption 

Type ranged

Activity fraction Significant to 

external exposureb

234Ua F F-S 9.12 × 10-1

235Ua F F-S 3.16 × 10-2

236Ua F F-S 2.64 × 10-3

238Ua F F-S 5.33 × 10-2 X 99Tc M F-M Trace X 237Np S M-S 9.58 × 10-5

238Puc S M-S 1.79 × 10-5 X 239Puc S M-S 1.79 × 10-5 X 240Puc S M-S 1.79 × 10-5 X 241Amc S M-S 1.79 × 10-5 X 228Th S F-S 1.15 × 10-4

230Th S F-S 3.47 × 10-4

231Th S F-S Trace 232Th S F-S 3.6 × 10-6

234Th M F-S Trace X 234mPa M M-S (In equilibrium with 234Th) X

a. UF6 and UO2F2 are considered type F materials (Hill, p. 14.7). U3O8 is considered type S 

(Hill, p. 14.7). Most material should be UF6 feed. Most bioassay results indicate that 

uranium acts as a type F material (Hill, p. 14.5). To be claimant favorable assume type S 

unless otherwise indicated in the bioassay records.

b. 238U feeds 234mPa with a high-energy beta that is also of concern. 

c. Americium and plutonium not distinguished in analysis.

d. Always use bioassay information to determine absorption class, when available

 
Effective Date: 11/21/2003 Revision No. 00 Document No. ORAUT-TKBS-0015-2 Page 19 of 33

Table 2.3.2-1. Radionuclides of concern for Buildings X-342 and X-342A. 

Facility/process X-342 Fluorine Generation Facility 

and X-342A Fixed Feed Facility

Years of operation 1954 – 2001

Radionuclides 

of concern

Most 

Probable 

Absorption 

Type

Absorption 

Type ranged

Activity fraction Significant to external 

exposureb

234U F F-S 8.46 × 10-1

235U F F-S 3.48 × 10-2

236U F F-S 4.69 × 10-3

238U F F-S 1.14 × 10-1 X 99Tc M F-M Trace X 237Np S M-S 3.35 × 10-4

238Puc S M-S 1.33 × 10-5 X 239Puc S M-S 1.33 × 10-5 X 240Puc S M-S 1.33 × 10-5 X 241Amc S M-S 1.33 × 10-5 X 228Th S F-S 1.05 × 10-4

230Th S F-S 1.06 × 10-4

231Th S F-S Trace 232Th S F-S Trace 234Tha M F-S Trace X 234mPaa M M-S (In equilibrium with 234Th) X

a. 234Th/234mPa are found in equilibrium and are type M for GDPs. 99Tc is type F for GDPs, based on the 

more conservative modes (RPM, p. 15).

b. 238U feeds 234mPa with a high-energy beta that is also of concern.

c. Americium and plutonium not distinguished in analysis.

d. Always use bioassay information to determine absorption type, when available

 

 
Effective Date: 11/21/2003 Revision No. 00 Document No. ORAUT-TKBS-0015-2 Page 20 of 33

 Table 2.3.3-1. Radionuclides of concern for Building X-343. 

Facility/process X-343 Fixed Feed Facility

Years of operation 1954 – 2001

Radionuclides 

of concern

Most 

Probable 

Absorption 

Type

Absorption 

Type ranged

Activity fraction Significant to external 

exposureb

234U F F-S 8.06 × 10-1

235U F F-S 3.45 × 10-2

236U F F-S 2.31 × 10-3

238U F F-S 1.57 × 10-1 X

99Tc M F-M Trace X

237Np S M-S 8.78 × 10-5

238Puc S M-S 6.26 × 10-5 X

239Puc S M-S 6.26 × 10-5 X

240Puc S M-S 6.26 × 10-5 X

241Amc S M-S 6.26 × 10-5 X

228Th S F-S 2.49 × 10-5

230Th S F-S 1.95 × 10-4

231Th S F-S Trace

232Th S F-S Trace

234Tha M F-S Trace X

234mPaa M M-S (In equilibrium with 234Th) X

a. 234Th/234mPa are found in equilibrium and are type M for GDPs. 99Tc is type F for GDPs 

that based their DAC on the more conservative modes (RPM, p. 15). 

b. 238U feeds 234mPa with a high-energy beta that is also of concern. 

c. Americium and plutonium not distinguished in analysis. 

d. Always use bioassay information to determine absorption type, when available
Effective Date: 11/21/2003 Revision No. 00 Document No. ORAUT-TKBS-0015-2 Page 21 of 33

Table 2.3.4-1. Radionuclides of concern for Building X-344. 

Facility/process

X-344 UF4 conversion to UF6 conversion facility 

Cylinder Transferring and Transfer Facility

Years of operation 1958 – 1962 and 1962 – 2001

Radionuclides 

of concern

Most 

Probable 

Absorption 

Type

Absorption 

Type ranged

Activity fraction Significant to external 

exposureb

234U Se F-S 7.44 × 10-1

235U Se F-S 3.20 × 10-2

236U Se F-S 4.9 × 10-4

238U Se F-S 2.23 × 10-1 X

99Tc M F-M Trace X

237Np S M-S 2.37 × 10-5

238Puc S M-S 3.48 × 10-6 X

239Puc S M-S 3.48 × 10-6 X

240Puc S M-S 3.48 × 10-6 X

241Amc S M-S 3.48 × 10-6 X

228Th S F-S 9.95 × 10-6

230Th S F-S 1.42 × 10-4

231 Th S F-S Trace

232Th S F-S Trace

234Tha M F-S Trace X

234mPaa M M-S (In equilibrium with 234Th) X

a. 234Th/234mPa are found in equilibrium and are type M for GDPs. 99Tc is type F for GDPs that 

based their DAC on the more conservative modes (RPM, p. 15).

b. 238U feeds 234mPa with a high-energy beta that is also of concern.

c. Americium and plutonium not distinguished in analysis.

d. Always use bioassay information to determine absorption type, when available

e. Absorption type for this facility has indicated class S in many bioassay results (Thomson 

2003)
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Table 2.3.5-1. Radionuclides of concern in Building X-345. 

Facility/process X-345 SNM Storage Area – HEU storage

Years of operation 1954 – 2003

Radionuclides 

of concern

Most 

Probable 

Absorption 

Type

Absorption 

Type ranged

Activity fraction Significant to external 

exposureb

234U F F-S 9.78 × 10-1

235U F F-S 1.68 × 10-2

236U F F-S 1.19 × 10-3

238U F F-S 2.16 × 10-3 X

99Tc M F-M Trace X

237Np S M-S 2.04 × 10-3

238Puc S M-S Trace X

239Puc S M-S Trace X

240Puc S M-S Trace X

241Amc S M-S Trace X

228Th S F-S Trace

230The S F-S 1.2 × 10-1

231Th S F-S Trace

232Th S F-S Trace

234Tha M F-S Trace X

234mPaa M M-S (In equilibrium with 234Th) X

a. 234Th/234mPa are found in equilibrium and are type M for GDPs. 99Tc is type F for GDPs that 

based their DAC on the more conservative modes (RPM, p. 15).

b. 238U feeds 234mPa with a high-energy beta that is also of concern.

c. Americium and plutonium not distinguished in analysis.

d. Always use bioassay information to determine absorption type, when available.

e. 230Th is a significant inhalation hazard in this building, see section 2.3.5.

 
Effective Date: 11/21/2003 Revision No. 00 Document No. ORAUT-TKBS-0015-2 Page 23 of 33

Table 2.3.6-1. Radionuclides of concern in Building X-700. 

Facility/process Converter Shop and Cleaning Area

Years of operation 1954 – 2003

Radionuclides 

of concern

Most 

Probable 

Absorption 

Type

Absorption 

Type ranged

Activity fraction Significant to external 

exposureb

234U Se F-S 5.97 × 10-1

235U Se F-S 3.14 × 10-2

236U Se F-S 2.55 × 10-3

238U Se F-S 3.64 × 10-1 X

99Tc M F-M Trace X

237Np S M-S 1.37 × 10-3

238Puc S M-S 5.24 × 10-5 X

239Puc S M-S 5.24 × 10-5 X

240Puc S M-S 5.24 × 10-5 X

241Amc S M-S 5.24 × 10-5 X

228Th S F-S 3.74 × 10-4

230Th S F-S 3.17 × 10-3

231Th S F-S Trace

232Th S F-S 3.23 × 10-4

234Tha M F-S Trace X

234mPaa M M-S (In equilibrium with 234Th) X

a. 234Th/234mPa are found in equilibrium and are type M for GDPs. 99Tc is type F for GDPs 

that based their DAC on the more conservative modes (RPM, p. 15).

b. 238U feeds 234mPa with a high-energy beta that is also of concern.

c. Americium and plutonium not distinguished in analysis.

d. Always use bioassay information to determine absorption type, when available

e. Absorption type for this facility has indicated class S in many bioassay results. (Thomson 

2003) 
Effective Date: 11/21/2003 Revision No. 00 Document No. ORAUT-TKBS-0015-2 Page 24 of 33

Table 2.3.7-1. Radionuclides of concern in Building X-705. 

Facility/process X-705 Decontamination and Recovery

Years of operation 1954 – present

Radionuclides 

of concern

Most 

Probable 

Absorption 

Type

Absorption 

Type ranged

Activity fraction Significant to external 

exposureb

234U Se F-S 8.87 × 10-1

235U Se F-S 3.43 × 10-2

236U Se F-S 1.86 × 10-2

238U Se F-S 5.88 × 10-2 X

99Tc M F-M Trace X

237Np S M-S 1.60 × 10-4

238Puc S M-S 8.79 × 10-5 X

239Puc S M-S 8.79 × 10-5 X

240Puc S M-S 8.79 × 10-5 X

241Amc S M-S 8.79 × 10-5 X

228Th S F-S 1.30 × 10-4

230Th S F-S 6.66 × 10-4

231Th S F-S Trace

232Th S F-S 3.37 × 10-5

234Tha M F-S Trace X

234mPaa M M-S (In equilibrium with 234Th) X

a. 234Th/234mPa are found in equilibrium and are class M for GDPs. 99Tc is class F for GDPs 

that based their DAC on the more conservative modes (RPM, p. 15).

b. 238U feeds 234mPa with a high-energy beta that is also of concern.

c. Americium and plutonium not distinguished in analysis.

d. Always use bioassay information to determine solubility class, when available.

e. Absorption type for this facility has indicated class S in many bioassay results. (Thomson 

2003)
Effective Date: 11/21/2003 Revision No. 00 Document No. ORAUT-TKBS-0015-2 Page 25 of 33

Table 2.3.8-1. Radionuclides of concern for Building X-705E. 

Facility/process X-705E Oxide Conversion

Years of operation 1957 – 1978

Radionuclides 

of concern

Most 

Probable 

Absorption 

Type

Absorption 

Type ranged

Activity fraction Significant to external 

exposureb

234U Se F-S 8.87 × 10-1

235U Se F-S 3.43 × 10-2

236U Se F-S 1.86 × 10-2

238U Se F-S 5.88 × 10-2 X

99Tc M F-M Trace X

237Np S M-S 1.60 × 10-4

238Puc S M-S 8.79 × 10-5 X

239Puc S M-S 8.79 × 10-5 X

240Puc S M-S 8.79 × 10-5 X

241Amc S M-S 8.79 × 10-5 X

228Th S F-S 1.30 × 10-4

230Th S F-S 6.66 × 10-4

231Th S F-S Trace

232Th S F-S 3.37 × 10-5

234Tha M F-S Trace X

234mPaa M M-S (In equilibrium with 234Th) X

a. 234Th/234mPa are found in equilibrium and are class M for GDPs. 99Tc is class F for GDPs 

that based their DAC on the more conservative modes (RPM, p. 15).

b. 238U feeds 234mPa with a high-energy beta that is also of concern.

c. Americium and plutonium not distinguished in analysis.

d. Always use bioassay information to determine solubility class, when available.

e. Absorption type for this facility has indicated class S in many bioassay results. (Thomson 

2003)
Effective Date: 11/21/2003 Revision No. 00 Document No. ORAUT-TKBS-0015-2 Page 26 of 33

 Table 2.3.9-1. Radionuclides of concern for Building X-710. 

Facility/process X-710 Analytical Labs, Process and Materials

Years of operation 1954 – 2003

Radionuclides 

of concern

Most 

Probable 

Absorption 

Type

Absorption 

Type ranged

Activity fraction Significant to external 

exposureb

234U F F-S 9.18 × 10-1

235U F F-S 2.70 × 10-2

236U F F-S 1.75 × 10-2

238U F F-S 4.69 × 10-2 X

99Tc M F-M Trace X

237Np S M-S 1.80 × 10-3

238Puc S M-S 7.25 × 10-4 X

239Puc S M-S 7.25 × 10-4 X

240Puc S M-S 7.25 × 10-4 X

241Amc S M-S 7.25 × 10-4 X

228Th S F-S 3.49 × 10-4

230Th S F-S 3.94 × 10-3

231Th S F-S Trace

232Th S F-S 4.61 × 10-5

234Tha M F-S Trace X

234mPaa M M-S (In equilibrium with 234Th) X

a. 234Th/234mPa are found in equilibrium and are type M for GDPs. 99Tc is type F for GDPs 

that based their DAC on the more conservative modes (RPM, p. 15). 

b. 238U feeds 234mPa with a high-energy beta that is also of concern.

c. Americium and plutonium not distinguished in analysis.

d. Always use bioassay information to determine absorption type, when available
Effective Date: 11/21/2003 Revision No. 00 Document No. ORAUT-TKBS-0015-2 Page 27 of 33

Table 2.3.10-1. Radionuclides of concern for Building X-720. 

Facility/process X-720 Compressor Shop& High Bay

Years of operation 1954 – 2003

Radionuclides 

of concern

Most 

Probable 

Absorption 

Type

Absorption 

Type ranged

Activity fraction Significant to external 

exposureb

234U F F-S 7.77 × 10-1

235U F F-S 3.45 × 10-2

236U F F-S 8.9 × 10-4

238U F F-S 1.86 × 10-1 X

99Tc M F-M Trace X

237Np S M-S Trace

238Puc S M-S 3.08 × 10-4 X

239Puc S M-S 3.08 × 10-4 X

240Puc S M-S 3.08 × 10-4 X

241Amc S M-S 3.08 × 10-4 X

228Th S F-S 5.64 × 10-4

230Th S F-S 4.68 × 10-4

231Th S F-S Trace

232Th S F-S Trace

234Tha M F-S Trace X

234mPaa M M-S (In equilibrium with 234Th) X

a. 234Th/234mPa are found in equilibrium and are type M for GDPs. 99Tc is type F for GDPs that 

based their DAC on the more conservative modes (RPM, p. 15). 

b. 238U feeds 234mPa with a high-energy beta that is also of concern.

c. Americium and plutonium not distinguished in analysis.

d. Always use bioassay information to determine absorption type, when available
Effective Date: 11/21/2003 Revision No. 00 Document No. ORAUT-TKBS-0015-2 Page 28 of 33

Table 2.3.11-1. Radionuclides of concern in Building X-744G. 

Facility/process X-744G Smelter for Aluminum recovery

Years of operation 1961 – 1983

Radionuclides 

of concern

Most 

Probable 

Absorption 

Type

Absorption 

Type ranged

Activity fraction Significant to external 

exposureb

234U F F-S 9.44 × 10-1

235U F F-S 3.26 × 10-2

236U F F-S 2.57 × 10-3

238U F F-S 1.88 × 10-2 X

99Tc M F-M Trace X

237Np S M-S 4.61 × 10-4

238Puc S M-S 2.21 × 10-4 X

239Puc S M-S 2.21 × 10-4 X

240Puc S M-S 2.21 × 10-4 X

241Amc S M-S 2.21 × 10-4 X

228Th S F-S 3.08 × 10-4

230Th S F-S 1.04 × 10-3

231Th S F-S Trace

232Th S F-S 4.92 × 10-5

234Tha M F-S Trace X 234mPaa M M-S (In equilibrium with 234Th) X

a. 234Th/234mPa are found in equilibrium and are type M for GDPs. 99Tc is type F for GDPs that 

based their DAC on the more conservative modes (RPM, p. 15). 

b. 238U feeds 234mPa with a high-energy beta that is also of concern.

c. Americium and plutonium not distinguished in analysis.

d. Always use bioassay information to determine absorption class, when available.

Table 2.4.2-1. Reactor returns fed to cascade. 

Fiscal year

Amount fed 

(MTU)

Enrichment 

(%235U) Source Remarks

1955 105.8 0.64 – 0.68 Paducah

1956 54.5 0.64 – 0.68 Paducah Fed May – Sept. 1955

1956 293.4 0.64 – 0.68 Oak Ridge

1957 6.2 0.64 – 0.68 Paducah

1958 64.2 0.64 – 0.68 Paducah

1970 168.1 0.64 – 0.68 Paducah Fed Oct. & Nov. 1969

1974 398.8 0.64 – 0.68 Paducah Fed Jan. 1974

1974 – 1978 1.86 2 – 50 PORTS Oxide Conversion

1968 – 1977 0.15 78 – 80 Division of International Affairs

1977 – 1998 0.15 78 – 97 Babcock & Wilcox

1969 – 1993 0.07 78 AEC Office of Safeguards & Materials 

Management

1997 – 1998 1.10 56 – 82 France

1997 – 1998 0.33 80 NUMEC

TOTAL 1,094.66

Source: Table 2.2.2.5-1, BJC (2000, p. 22).
Effective Date: 11/21/2003 Revision No. 00 Document No. ORAUT-TKBS-0015-2 Page 29 of 33

REFERENCES

ANL (Argonne National Laboratory) 2003, “Uranium Hexafluoride”, 

http://web.ead.anl.gov/uranium/about/index.cfm. 

BJC (Bechtel Jacobs Company LLC) 2000, Recycled Uranium Mass Balance Project, Portsmouth, 

Ohio Site Report, BJC/PORTS-139/R1, U. S. Department of Energy, Office of Environmental 

Management, Washington, DC 

Cardarelli, J., II, 1997, NIOSH Health Hazard Evaluation Report, HEJA 96-1298-2651, National 

Institute of Occupational Safety and Health. 

DOE (U. S. Department of Energy) 1997, Linking Legacies Connecting the Cold War Nuclear 

Weapons Production Processes to Their Environmental Consequences, Office of 

Environmental Management, Washington, DC 

DOE (U. S. Department of Energy) 2000a, Independent Investigation of the Portsmouth Gaseous 

Diffusion Plant, Volume 1, “Past Environment, Safety, and Health Practices,” Office of 

Oversight Environment, Safety, and Health, Washington, DC. 

DOE (U. S. Department of Energy) 2000b, Independent Investigation of the Portsmouth Gaseous 

Diffusion Plant, Volume 2, “Current Environment, Safety, and Health Practices”, Office of 

Oversight Environment, Safety, and Health, Washington, DC. 

DOE (U. S. Department of Energy) 2000c, Guide of Good Practices for Occupational Radiological 

Protection in Uranium Facilities, DOE Standard DOE-STD-1136-2000, DOE ES&H Technical 

Information Services, August 2000

HP-103, RPM HP-103 “Monitoring Skin Decontamination,” Training Lesson Plan. 

Hill, R.L., and D.J.Strom, June 1993, Internal Dosimetry Technical Basis Manual for Portsmouth and 

Paducah Gaseous Diffusion Plants, PNL-8723 (UC-607), Pacific Northwest Laboratories,

Battelle Memorial Institute. 

NRC (U.S. Nuclear Regulatory Commission) 1999, Notice of Violation and Proposed Imposition of 

Civil Penalty, EA-99-080 – U.S. Enrichment Corporation, letter from J. E. Dyer to J. N. Adkins 

dated June 29, 1999. 

NRC (U. S. Nuclear Regulatory Commission) 1992, Information Notice No. 92-34: New exposure 

Limits for Airborne Uranium and Thorium, May 6, 1992.

Public Law 102-486, Energy Policy Act of 1992, codified throughout the U.S.C. 

USEC (United States Enrichment Corporation) 2003, ”The history of PORTS,” 

http://www.usec.com/v2001_02/HTML/Facilities_PortsOverview.asp, accessed August 21, 

2003.

Yggdrasil Institute 2003, “A Guide to Key Facilities and Sites at the Portsmouth Gaseous Diffusion 

Plant,” http://www.earthisland.org/yggdrasil/portsmouth_gdp.html, accessed August 20, 2003. 
Effective Date: 11/21/2003 Revision No. 00 Document No. ORAUT-TKBS-0015-2 Page 30 of 33

GLOSSARY

ALARA

Acronym for "As Low As Reasonably Achievable," means making every reasonable effort to 

maintain exposures to ionizing radiation as far below the dose limits as practical, consistent 

with the purpose for which the licensed activity is undertaken, taking into account the state of 

technology, the economics of improvements in relation to state of technology, the economics 

of improvements in relation to benefits to the public health and safety, and other societal and 

socioeconomic considerations, and in relation to utilization of nuclear energy and licensed 

materials in the public interest (see 10 CFR 20.1003).

Alpha radiation

A positively charged particle ejected spontaneously from the nuclei of some 

radioactive elements. It is identical to a helium nucleus that has a mass number of 4 

and an electrostatic charge of +2. It has low penetrating power and a short range (a 

few centimeters in air). The most energetic alpha particle will generally fail to penetrate 

the dead layers of cells covering the skin and can be easily stopped by a sheet of 

paper. Alpha particles are hazardous when an alpha-emitting isotope is inside the 

body. 

Background radiation

Radiation from cosmic sources; naturally occurring radioactive materials, including 

radon (except as a decay product of source or special nuclear material) and global 

fallout as it exists in the environment from the testing of nuclear explosive devices. It 

does not include radiation from source, byproduct, or special nuclear materials 

regulated by the Nuclear Regulatory Commission. The typically quoted average 

individual exposure from background radiation is 360 millirems per year. 

Becquerel

The derived SI unit of radioactive decay equal to 1 disintegration per second. 37 billion 

(3.7x1010) becquerels = 1 curie (Ci). 

Beta particle (Beta Radiation)

A charged particle emitted from a nucleus during radioactive decay, with a mass equal 

to 1/1837 that of a proton. A negatively charged beta particle is identical to an electron. 

A positively charged beta particle is called a positron. Large amounts of beta radiation 

may cause skin bums, and beta emitters are harmful if they enter the body. Beta 

particles may be stopped by thin sheets of metal or plastic. 

Cascade

The process system that is used to separate the isotopic streams of uranium-235 and 

uranium-238 in gaseous diffusion plants.

Cylinder

A large steel container used to store UF6. Cylinders are typically about 3.7 m (12 ft) 

long by 1.2 m (4 ft) in diameter and weigh about 9.1 to 12.7 metric tons (10 to 14 tons) 

when full of depleted UF6. 

Deep dose equivalent

The dose equivalent at the respective depth of 1.0 cm in tissue.
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Depleted UF6 

UF6 with a lower isotopic fraction of 235U than found in natural uranium. 

Depleted Uranium

Uranium having a percentage of uranium-235 smaller than the 0.7 percent found in natural 

uranium. It is obtained from spent (used) fuel elements or as byproduct tails, or residues, from 

uranium isotope separation.

Derived Air Concentration (DAC)

The concentration of radioactive material in air and the time of exposure to that radionuclide, in 

hours. An NRC licensee may take 2,000 hours to represent one ALI, equivalent to a committed 

effective dose equivalent of 5 rems (0.05 sievert). 

Derived concentration guidelines (DCG)

A calculated concentration that would result in an annual dose of 100 millirem.

Dose Equivalent

The product of absorbed dose in tissue multiplied by a quality factor, and then sometimes 

multiplied by other necessary modifying factors at the location of interest. It is expressed 

numerically in rems or sieverts (see 10 CFR 20.1003).

Dosimeter

A small portable instrument (such as a film badge, thermoluminescent or pocket dosimeter) for 

measuring and recording the total accumulated personnel dose of ionizing radiation.

Dosimetry

The science of assessing absorbed dose, dose equivalent, effective dose equivalent, 

etc., from external and/or internal sources of radiation.

Enriched UF6 

UF6 with a higher isotopic fraction of 235U than found in natural uranium. 

Enrichment

An isotopic separation process that increases the portion of the 235U isotope in relation 

to 238U in natural uranium. In addition to the enriched uranium, this process also 

produces uranium depleted in 235U (see depleted UF6 and tails).

Exposure

As used in the technical sense, exposure refers to a measure expressed in roentgens 

(R) of the ionization produced by photon radiation (i.e., gamma and X-rays) in air.

Film Badge

In general, a “film packet” that contains one or more pieces of film in a light-tight 

wrapping. The film when developed has an image caused by radiation that can be 

measured using an optical densitometer.

Gamma Radiation (Gamma Rays)

High-energy, short wavelength, electromagnetic radiation emitted from the nucleus. 

Gamma radiation frequently accompanies alpha and beta emissions and always 

accompanies fission. Gamma rays are very penetrating and are best stopped or 

shielded by dense materials, such as lead or depleted uranium. 
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Gaseous Diffusion Plant 

A facility where uranium hexafluoride gas is filtered, uranium-235 is separated from 

uranium-238, increasing the percentage of uranium-235 from 1 to about 3 percent. The 

process requires enormous amounts of electric power. 

Halflife 

The time in which one half of the atoms of a particular radioactive substance 

disintegrates into another nuclear form. Measured half-lives vary from millionths of a 

second to billions of years. Also called physical or radiological halflife 

Halflife, biological 

The time required for the body to eliminate one half of the material taken in by natural 

biological means. 

Halflife, effective 

The time required for a radionuclide contained in a biological system, such as a human 

or an animal, to reduce its activity by one-half as a combined result of radioactive 

decay and biological elimination. 

In vitro 

From the Latin, in glass, isolated from the living organism and artificially maintained, as 

in a test tube. 

In vivo 

From the Latin, in one that is living, occurring within the living.

Monitoring of Radiation 

Periodic or continuous determination of the amount of ionizing radiation or radioactive 

contamination present in a region, as a safety measure, for the purpose of health or 

environmental protection. Monitoring is done for air, surface, & ground water, soil & 

sediment, equipment surfaces, and personnel (for example, bioassay or alpha scans).

Neutron

An uncharged elementary particle with a mass slightly greater than that of the proton, 

and found in the nucleus of every atom heavier than hydrogen. 

Non-stochastic effect 

The health effects, the severity of which vary with the dose and for which a threshold is 

believed to exist. Radiation-induced cataract formation is an example of a nonstochastic effect (also called a deterministic effect) (see 10 CFR 20.1003). 

Rad 

The special unit for radiation absorbed dose, which is the amount of energy from any 

type of ionizing radiation (e.g., alpha, beta, gamma, neutrons, etc.) deposited in any 

medium (e.g., water, tissue, air). A dose of one rad means the absorption of 100 ergs 

(a small but measurable amount of energy) per gram of absorbing tissue (100 rad = 1 

gray).

Radiation

Alpha, beta, neutron, and gamma ray (i.e., photon) radiation.
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Radiation Exposure Monitoring System (REMS) 

An online DOE database that contains records of personal dosimetry information.

Radioactivity

The spontaneous emission of radiation, generally alpha or beta particles, often 

accompanied by gamma rays, from the nucleus of an unstable isotope. Also, the rate 

at which radioactive material emits radiation. Measured in units of becquerels or 

disintegrations per second.

rem

(1) The amount of ionizing radiation required to produce the same biological effect as 

one rad of high-penetration x-rays. (2) A unit for measuring absorbed doses of 

radiation, equivalent to one roentgen of x-rays or gamma rays. 

Rotengen

A unit of radiation exposure equal to the quantity of ionizing radiation that will produce one 

electrostatic unit of electricity in one cubic centimeter of dry air at 0°C and standard 

atmospheric pressure. 

Sievert (Sv) 

The international system (SI) unit for dose equivalent equal to 1 Joule/kilogram. 1

sievert = 100 rem.

Shallow Dose Equivalent (SDE)

The dose equivalent at the respective depth of 0.07 mm of the skin or an extremity.

Tails

The product stream of depleted UF6 (i.e., lower isotopic fraction of 235U than found in 

natural uranium) that results from the enrichment process. For gaseous diffusion at 

PORTS, tails are loaded into cylinders and placed in a UF6 cylinder storage yard.

Thermoluminescent dosimeter (TLD)

A small device used to measure radiation by measuring the amount of visible light 

emitted from a crystal in the detector when exposed to ionizing radiation. 

Uranium hexafluoride (UF6) cylinder storage yard

Storage yards at the Paducah and Portsmouth Gaseous Diffusion Plants and Oak 

Ridge K-25 site. These yards maintain cylinders containing depleted UF6. The 

cylinders, which typically weigh 10 and 14 tons, contain depleted UF6 that has cooled 

to a solid form.